Use of polyvinylpyrrolidone as a soil-suspending agent



3,000,830 USE F POLYVINYLPYRROLIDONE AS A SUE-SUSPENDING AGENT Wiilie Fong, Richmond, and Wilfred H. Ward and Harold P. Lundgren, Berkeley, Calif., assignors to the United States of Americans represented by the Secretary of A riclllture No Drawing. Filed Dec. 5, 1952, Ser. No. 324,423

7 Claims. (Cl. 252-117) (Granted under Title 35, US. Code (1952), sec. 266) A non-exclusive, irrevocable, royalty-free license in the invention herein described, for all governmental purposes, throughout the world, with the power to grant sublicenses for such purposes, is hereby granted to the Government of the United States of America.

This invention relates to washing procedures particularly to the washing of textile materials such as fabrics and fibers with aqueous media. In particular 'the invention concerns the use of polyvinylpyrrolidone in the aqueous washing medium whereby to minimize the redeposition of soil during the Washing procedure.

it is well known in the art that a successful Washing operation involves two separate factors, i.e., (a) the removal of dirt from the textile material and (b) keeping the soil suspended in the medium so that it will not be re-deposited on the textile. in general aqueous Washing media containing soap fulfill both of these criteria as soap not only is a good soil remover but also keeps the removed soil in suspension so that little re-deposition takes place. However, the present trend is toward the use of anionic synthetic detergents such as the alkyl benzene sulphonates since these agents can be used in hard Water areas as their detersive power is not decreased by the presence oi calcium and magnesium ions. However, these anionic detergents have the disadvantage that their suspending power is poor. Whereas they are very effective from the standpoint of're'r'noving soil they are not so effective in preventing re-deposition and so cotton fabrics washed with such agents will be grayer than when using soap. In order to overcome this disadvantage, various soil suspending agents are commonly added to the anionic detergents. One of the most commonly used agents is sodium carboxymethyl cellulose.

It has now been found'that polyvinylpyrrolidone has useful soil-suspending properties and when added to aqueous washing media the degree of soil re-deposition is greatly reduced. As well known in the art, polyvinyl- .pyrrolidone-is not a single, individual compound but may be obtained in almost any degree of polymerization. The degree of polymerization is most easily expressed in terms of average molecular weight. Although this invention comprises in its broad aspect the use of polyvinylpyrrolidone having any degree of polymerization and which is soluble in water at least-to the extent of about .001% to about 0.1%, it is to be understood that not all the polymers possess the same degree of efiectiveness. Thus as shown in the examples infra, polyvinylpyrrolidones having an average molecular Weight from about 15,000 to about 40,000 exhibit maximum soil-suspending activity. For this reason it is preferred to use a polyvinylpyn'olidone of such molecular weight range as a soilsuspending agent in washing operations.

A particular advantage of polyvinylpyrrolidone as a soil-suspending agent is that it retains its effectiveness even in the presence of relatively high concentrations of calcium such as would be present in hard water. As

Patented Sept. 19, E961 the above range butin general increasing the concentration above 0.1% gives little if any added protection. If desired, the polyvinylpyrrolidone can be incorporated with the detergent so as to form a composition which on dissolving in water furnishes the desired washing medium. To this end, the detergent is mixed with about 2 to 10% of the polyvinylpyrrolidone.

Incarrying out washing operations in accordance with this invention, the fabric or other textile material is agitated in the usual manner preferably at elevated temperatures as commonly used in laundries with the aqueous media containing the polyvinylpyrrolidone and the detergent. As the detergent one may use any of the materials commonly used for washing purposes.

The detergent may be, for example, of the anionic or non-ionic types. In the first category are included ordinary soaps, that is, sodium or potassium salts of the higher fatty acids, or, usually, mixtures of higher fatty acids as are derived from naturally-occurring oils and fats. Also included in the anionic category are the detergentsof the sulphonate or sulphate type. As well knownin the art, a multitude of such materials are avail able, including the alkyl (C -C sulphates, the alkyl (C -C sulphonates, the alkyl (C3 C1S) aromatic sulphonates, the monoor di-alkyl (C -C esters of sulphosuccinic acid, sulphonated or sulphated amides of the higher fatty acids such as N-sulphoethyl stearamide, and so forth. These compounds are generally employed in the form of their salts, i.e., their sodium, potassium, ammonium or amine salts. Some of the particular detergents which may be used are: sodium octyl sulphate,

sodium nonyl sulphate, sodium decyl sulphate, sodium undecyl sulphate,- sodium dodecyl sulphate, sodium tridecyl sulphate, sodium tetradecyl sulphate, sodium pentadecyl sulphate, sodium hexadecyl sulphate, sodium heptadecyl sulphate, sodium octadecyl sulphate, sodium oleyl sulphate, .sodium octyl sulphonate, sodium nonyl sulphonate, sodium decyl sulphonate, sodium undecyl sulphonate, sodium dodecyl sulphonate, sodium tridecyl. sulphonate, sodium tetradecyl sulphonate, sodium pentadecyl sulphonate, sodium hexadecyl sulphonate, sodium octadecyl sulphonate, sodium oleyl sulphonate, sodium salt of di-octvl sulpho-sucoinate, sodium octyl benzene sulphonate, sodium nonyl benzene sulphonate, sodium decyl benzene sulphonate, sodium undecyl benzene sulphonate, sodium dodecyl benzene sulphonate, sodium tridecyl benzene sulphonate, sodium tetradecyl benzene sulphonate, sodium pentadecyl benzene sulphonate, sodium hexadecyl benzene sulphonate, sodium heptadecyl benzene sulphonate, sodium octadecyl benzene sulphonate, sodium tri (is opropyl) benzene sulphonate, sodium tri (isobutyl) benzene sulphonate, sodium tri (isopropyl) naphthalene sulphonate, sodium tri (isobutyl) naphthalene sulphonate, and so forth. The commercially available detergents are generally not pure compounds but are mixturesof homologous compounds and are quite sat 'aoodeso isfactory. Thus for example, the sodium alkyl benzene sulphonate wherein the alkyl group contains 12 to 18 carbon atoms is a well known detergent. Others are: a mixture of sodium alkyl sulphates consisting mostly of sodium lauryl sulphate; a mixture of sodium alkyl phenol sulphonates wherein the alkyl group contains 12 to 18 carbon atoms; and a mixture of sodium alkyl sulphonates wherein the alkyl-group contains 10 to 18 carbon atoms. As non-anionic detergents one may employ polyalkylene glycol esters, ethers and'thioethers ofthe following types:

wherein the Rs represent long chain 'alkylradicalsiof 8 to 12 carbon atoms and n is an 'integ'er' from-about '4 to 12. Other non-anionic detergents are thel'ong-chain fatty acid esters of anhydrosorbitol, or the polyethylene glycol addition products of suchesters: Itisevident that the particular detergent used is not critical except "that one should be chosen which is generally "useful in emulsifying and detergent applications.

The concentration of the detergent is not critical a wide range and depending on the soil removal efficiency of the particular agent, the range off-concentration may be from about 0.05% to about 0.5%.- If desired, the soil removal efiicieney of the detergent maybe increased by addition to the aqueous medium of any of th'eusual types of builders such as sodium 'hexanietaphos'phate, tetra-sodium pyrophosphate, sodium ti-ipolyphosphate, trisodium phosphate, borax,"sodium carbonategsodiurnsilioate, sodium metasilicate, and'so forth.

The following examples illustrate the invention in @greater detail. The known soil-suspending agent, *sodium'carboxyrnethyl cellulose, was employed insoine of the experiments for comparative purposes. In all the experiments, carbon black was added to the washing media to test the soil-suspending-power of the various materials under test. Obviouslyin*practice ofjtheinvention, no carbon black or'oth'e'rsoil would be added to thewashing medium.

Example I A series of experiments were carried out in which'clcan swatches of cloth were agitated in an aqueous medium containing a synthetic detergent, various soil-suspending agents at various concentration levels, and carbon black. The treated swatches were then subjected to reflectance measurements to measure the amount of soil (carbon black) which had been deposited on the fabric thus to compare the effectiveness of the soil-suspending agents. The reflectance values are an index of the'cleanness of the cloth; the higher the proportion-oflight reflected the cleaner the cloth. In the examples theabbreviations PVP and AMW stand for polyvinylpyrrolidone-and average molecular weight, respectively. The experiments were carried out as follows:

A standard washing medium was prepared containing: water; sodium alkyl (C -C benzene sulpho'nate, 0.12%; sodium tripolyphosphate, 0.08%;fsodiumcarbonate, 0.04%; and carbon black, 301%. The pH of this solution was about 10.3. To samples of the standard medium were added various soil-suspending agents as hereinafter indicated. Each solution so prepared was tested as follows:

Two hundred cc. of the test solution was placed in a pint jar together with a s'watchof a standard bleached muslin (cotton) cloth and 20%" stainles's s't'e el balls. The far was then sealed and placed in a Launderonieter agitated by rotation at 140? -F. for minutes. The test swatch was then removed, frin'sed 4ftnne's distilled water and agitated with 200cc. of distilled water in the Launderometer for1 minutes at '140 F. washing in distilled water was done to remove loosely i adherent carbon black sothat the results would relate solely to adsorbed soil. The treated swatch was then dried in air, ironed, and the reflectance measured.

The materials, and proportions used and the results obtained are tabulated below:

Reflectance (in percent) of washed samples using various soil-suspending agents at various concentration levels Goncentratlon of soil- Sodium suspend- PVP, PVP, PV. PVP, PVP, caring agent, A.M.W. A.M.W. A.M.W A.M.W A.M.W. boxypercent 15,000 40,000 100,000 250,000 750,000 mefiiyl ce nlose The reflectance of the original cloth sample was Exdmple II A standard washing medium was prepared containing: water; sodium alkyl (Cm-C "benzene sulphonate, 0.12%; andcarbon black, 0.1%.- The pH was adjusted to 10 by the addition of sodium hydroxide and glycine was added as a buffering agent. To samples of the standard medium were added varlous concentrations of calcium chloride to furnish media of various hardnesses and to these media Were addedpolyvinylpyrrolidone (concentration 0.01%, average molecular weight 40,000) and sodium carboxymethylcellulose in a concentration of 0.01%. The resulting solutions were used for washing samples of cloth in the same manner as in Example I and the washed swatches were tested in the same manner as aforesaid. I

The results are summarized below:

Reflectance of washed samples, expressed in percent Water-hardness, expressed'as p;p.m.

of 02.60; PVP, A.M.W. Sodium car- 40,000 cone. boxymethyl- 0.01% cellulose cone.

The reflectance of the original cloth saniples was 70%.

Having thus described our invention we claim:

, 1. A process for removing soil from a textile material and minimizing the re-depos-ition of removed soil which comprises washing thematerial with a solution comprising water, organic surfaceactive detergent, and polyvinylpyrrolidone.

2. The process of claim 1 wherein the polyvinylpyrrolidone has an average molecular weight from about 15,000 to about 40,000.

3. A washing solution which is effective not only to remove soil from textile materials but also to minimize re-deposition of removedsoil comprising water, an or ganic'surfac'enctive detergent, and polyvinylpyrrolidone. I 4. The composition of claim 3 wherein the polyvinylpyrrolidone has an average molecular weight from about 15,000 to about 40,000.

5. A composition soluble in water to form a washing solution which is effective not only to remove soil from textile materials but also to minimize re-deposition of removed soil, comprising an organic surface-active detergent and polyvinylpyrroli'done.

6. The composition of claim 5 wherein the polyvinyl- 5 pyn-olidone has an average molecular weight of about 2,566,501 15,000 to about 40,000. 2,707,959

7. The composition of claim 5 wherein the detergent is a sodium alkyl benzene sulphonate wherein the alkyl group contains 12 to 18 carbon atoms. 5 850,328

References Cited in the file of this patent UNITED STATES PATENTS 2,283,199 Flett May 19, 1942 6 Smith et a1. Sept. 4, 1951 Shel'anski May 10, 1955 FOREIGN PATENTS Germany Sept. 22, 1952 OTHER REFERENCES Vinyl and Related Polymers, Schildknecht, Wiley and Sons, N.Y. (1952), pages 674-675. 

1. A PROCESS FOR REMOVING SOIL FROM A TEXTILE MATERIAL AND MINIMIZING THE RE-DEPOSITION OF REMOVED SOIL WHICH COMPRISES WASHING THE MATERIAL WITH A SOLUTION COMPRISING WATER, AN ORGANIC SURFACE-ACTIVE DETERGENT, AND POLYVINYLPYRROLIDONE. 